iOS - Navigation 设置副标题

twoLineTitleView.m

    UILabel *titleLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 0, 0)];
    titleLabel.backgroundColor = [UIColor clearColor];
    titleLabel.textColor = kColorNavTitle;
    titleLabel.font = [UIFont boldSystemFontOfSize:17];
    titleLabel.text = [[_myCodeTree.path componentsSeparatedByString:@"/"] lastObject];
    [titleLabel sizeToFit];
    
    UILabel *subTitleLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 22, 0, 0)];
    subTitleLabel.backgroundColor = [UIColor clearColor];
    subTitleLabel.textColor = kColorDark7;
    subTitleLabel.font = [UIFont systemFontOfSize:12];
    subTitleLabel.text = _myCodeTree.path;
    [subTitleLabel sizeToFit];
    
    UIView *twoLineTitleView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, MAX(subTitleLabel.frame.size.width, titleLabel.frame.size.width), 30)];
    [twoLineTitleView addSubview:titleLabel];
    [twoLineTitleView addSubview:subTitleLabel];
    
    float widthDiff = subTitleLabel.frame.size.width - titleLabel.frame.size.width;
    
    if (widthDiff > 0) {
        CGRect frame = titleLabel.frame;
        frame.origin.x = widthDiff / 2;
        titleLabel.frame = CGRectIntegral(frame);
    }else{
        CGRect frame = subTitleLabel.frame;
        frame.origin.x = ABS(widthDiff) / 2;
        subTitleLabel.frame = CGRectIntegral(frame);
    }
    
    self.navigationItem.titleView = twoLineTitleView;